There is an increasing demand for reducing the size of mounted components, and more importance is being placed on a technology capable of decreasing the size of a package and, thus, capable of reducing the size and weight of a semiconductor device.
Such a technology which has been developed is wafer-level packaging (WLP). In WLP, interconnects and electrodes of a circuit are provided on a semiconductor wafer, and encapsulated with a resin, and then, dicing of the semiconductor wafer is performed. Furthermore, high-density integration, more external connections, and the like have been required in recent years, and in order to satisfy such conditions, embedded waver-level ball grid array (eWLB) has been developed.
This method for manufacturing a package utilizes a technique that includes adhering a semiconductor chip onto a supporting substrate using an adhesive film and encapsulating the semiconductor chip.
The adhesive film, however, is required to fix the semiconductor chip onto the supporting substrate during an encapsulating step or the like and, on the contrary, is required to be removed along with the supporting substrate from the semiconductor chip after encapsulating. As such, the adhesive film is required to have contrary characteristics.
In Patent Document 1, there is disclosed a thermally contractible film in which an adhesive layer is laminated on both surfaces of a base material, wherein the thermally contractible film has a high contraction percentage under a temperature of 100° C. or less.
In Patent Document 2, there are disclosed a semiconductor adhesive film in which a resin layer A is laminated on one or both sides of a supporting film and a method that includes adhering the semiconductor adhesive film, having a coefficient of linear thermal expansion of 3.0×10−5/° C. at a temperature of 20° C. to 200° C., to a rear side of a lead frame to protect the lead frame with the supporting film and peeling the semiconductor adhesive film off after encapsulating. This supporting film is described as having a thermal contraction percentage of 0.15% or less when being heated at a temperature of 200° C. for two hours.
In Patent Document 3, there is disclosed a laminated sheet in which a contractible film layer and a constraining layer which constrains contraction of the contractible film layer are laminated. The contractible film layer is described as having a thermal contraction percentage of 30% to 90% at a temperature of 70° C. to 180° C. in the direction of main contraction.
In Patent Document 4, there is disclosed a dicing surface protecting sheet that uses a thermally contractible film having a thermal contraction percentage of 3% to 90% in the temperature range of 40° C. to 180° C. A processing method using this dicing surface protecting sheet is also described therein. However, Patent Document 4 does not describe using the dicing surface protecting sheet in a step of resin molding.
In Patent Document 5, there is disclosed a heat-peeled adhesive sheet in which a thermally expandable adhesive layer containing a foaming agent is laminated on at least one side of a base material that includes a composite film layer of a urethane polymer (meta) and an acrylic polymer. The heat-peeled adhesive sheet is described as having a thermal contraction percentage of 97% or greater at a temperature of 150° C.